Fish scales in sediments from off Callao,central Peru |
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| Institution: | 1. Institut de Ciències del Mar - CSIC, Ps. Marítim de la Barceloneta 37-49, E-08003 Barcelona, Spain;2. Red Sea Research Centre, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia;1. Department of Life and Environmental Sciences (DiSVA), Politechnic University of Marche, Ancona, Italy;2. UMR CNRS 6112 LPG-BIAF, University of Angers, Angers, France;3. Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Modena, Italy;4. Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207 CNRS MNHN UPMC, Muséum National d''Histoire Naturelle, Paris Cedex 05, France;1. Makah Fisheries Management, P.O. Box 115, Neah Bay, WA 98357, USA;2. Department of Earth & Ocean Sciences, University of Liverpool, Liverpool L69 3GP, UK;3. Northwest Indian Fisheries Commission, 6730 Martin Way East, Olympia, WA 98516, USA;4. Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA;1. Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia;2. The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, Perth, Australia;3. Environmental Molecular Science Laboratory (EMSL), Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA;4. GeoZentrum Nordbayern, University of Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany;5. Centre for Microscopy, Characterisation and Analysis (CMCA), The University of Western Australia, Perth, WA 6009, Australia;6. Department of Environment and Agriculture, Curtin University, GPO Box U1987, Perth, WA 6845, Australia |
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| Abstract: | We study fish scales as a proxy of fish abundance and preservation biases together with phosphorus from fish remains (Pfish) in a sediment core retrieved off Callao, Peru (12°1′S, 77°42′W; water depth=179 m; core length=52 cm). We interpret our results as a function of changing redox conditions based on ratios of redox-sensitive trace elements (Cu/Al, Mo/Al, Ni/Al, Zn/Al, V/Al), terrigenous indicators (Fe in clays, Ti, Al), and biogenic proxies (CaCO3, biogenic opal, total nitrogen, organic carbon, barite Ba). The core covers roughly 700 years of deposition, based on 210Pb activities extrapolated downcore and 14C dating at selected intervals. Our fish-scale record is dominated by anchovy (Engraulis ringens) scales followed by hake (Merluccius gayii) scales.The core presented an abrupt lithological change at 17 cm (corresponding to the early 19th century). Above that depth, it was laminated and was more organic-rich (10–15% organic carbon) than below, where the core was partly laminated and less organic-rich (<10%). The lithological shift coincides with abrupt changes in dry bulk density and in the contents of terrigenous and redox-sensitive trace elements, biogenic proxies, and fish scales. The remarkable increase in redox-sensitive trace elements in the upper 17 cm of the core suggests more reducing conditions when compared with deeper and older horizons, and is interpreted as an intensification of the oxygen minimum zone off Peru beginning in the early 19th century. Higher fish-scale contents and higher Pfish/Ptotal ratios were also observed within the upper 17 cm of the core. The behavior of biogenic proxies and redox-sensitive trace elements was similar; more reduced conditions corresponded to higher contents of CaCO3, Corg, total nitrogen and fish scales, suggesting that these proxies might convey an important preservation signal. |
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